Liquid filtering apparatus

Abstract

The present invention relates to an apparatus for filtering a liquid through a movable filter bed consisting of granular material, with continuous scavenging of the bed material and having the characterizing functions as follows: the filtering takes place in that liquid from a central inlet passes outward and upward through the filter bed. the filter bed in operation moves continuously downward, and the bed material is renewed continuously by supply to the upper portion (A) of the filter. the separation of impurities in the liquid takes place substantially in the central portion (C) of the filter and to a small extent in the portions located closest to the outlet. the washing of polluted bed material takes place in several steps, the first one thereof by fluidization of the material in the lowermost portion (D) of the filter, and the last one with liquid and air in the upper portion (A) of the filter. polluted bed material is drained in the lower portion of the filter together with transport liquid to a sand washing equipment located outside the filter, from which equipment transport liquid is returned to the lower portion (D) of the filter and washed material of the bed is transported to the upper portion (A) of the filter to be finally washed and distributed over the entire surface of the filter bed. in the apparatus, liquid can be filtered, in which the permissible size of the impurities is limited only by the dimension of the inlet conduit. Owing to the function of the apparatus the risk is eliminated that outgoing filtered liquid is polluted by release of dirt from the filter bed or from bed material returning to the bed after washing.

Dependencies are inferred from the claim text.